I think a "traitor" won't sell as many shirts as a young -unspoiled- promising star like Neymar/Lukaku/Aguero etc. Besides it's mostly clubs that sell shirts and not players (see Carragher being in the top10 PL shirts)
Anyone is better than us. Bolton are playing some good football at the moment so it's much like Welbeck's loan to Sunderland Yup, could very much be the case.